The present invention relates generally to a new and novel motor vehicle torque transfer case pump drive. More particularly, the present invention relates to a new and novel auxiliary hydraulic pump drive which is mounted in the front of a torque transfer case where it mounts to a motor vehicle transmission and includes a drive arrangement, such as a chain drive, a belt drive or a gear drive, to allow the auxiliary hydraulic pump to be driven directly from the torque transfer case, thus eliminating the requirement for a power take-off (PTO) adapter to drive the auxiliary hydraulic pump.
Four-wheel drive motor vehicles are becoming increasingly popular. Recently, certain motor vehicles have been provided with xe2x80x9cfull-timexe2x80x9d four-wheel drive systems. In such xe2x80x9cfull-timexe2x80x9d four-wheel drive systems, the torque transfer cases are typically provided with an interaxle differential for dividing torque between the front wheels and the rear wheels of the motor vehicle. The interaxle differential enables the front wheels and the rear wheels to rotate at different speeds, which occurs during normal turning of the motor vehicle or in the event that the front wheels and the rear wheels have tires with different diameters. However, to prevent excessive relative slipping between the front wheels and the rear wheels, as might occur when one set of wheels encounters a low-traction condition, such as ice, these torque transfer cases typically include a selectively engageable clutch which is operative to lock the interaxle differential upon sensing a predetermined amount of relative slippage between the front output shaft and the rear output shaft of the torque transfer case. Locking of the interaxle differential prevents any further relative overrun or differentiation between the front output shaft and the rear output shaft of the torque transfer case.
Known prior xe2x80x9cfull-timexe2x80x9d four-wheel drive systems have generally required a power take-off (PTO) adapter to drive an auxiliary hydraulic pump. Inclusion of a power take-off (PTO) adapter complicates the packaging of the torque transfer case in the motor vehicle and can have a negative impact on the cost and reliability of such torque transfer cases. In addition, in some motor vehicle applications, insufficient clearance is present to allow the use of a power take-off (PTO) adapter and thus the use auxiliary hydraulic pump is generally precluded in such situations.
A preferred embodiment of the present invention is, therefore, directed to a motor vehicle torque transfer case pump drive which is mounted in the front of a torque transfer case where it mounts to a motor vehicle transmission and includes a drive arrangement, such as a chain drive, a belt drive or a gear drive. This permits an auxiliary hydraulic pump to be driven directly from the torque transfer case, thus eliminating the need for a power take-off (PTO) adapter to drive the auxiliary hydraulic pump. The elimination of the need for a power take-off (PTO) simplifies the packaging of the torque transfer case in the motor vehicle and allows use of a hydraulic pump in applications where the power take-off (PTO) adapter has clearance issues in the motor vehicle. Alternatively, the transmission to torque transfer case adapter can be combined with the motor vehicle torque transfer case pump drive. The output connection would preferably use a standard SAE hydraulic pump mount which would facilitate placement of the hydraulic pump at a location that best fits the motor vehicle application without the added cost and mounting problems associated with a power take-off (PTO) adapter.
Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.